Measuring mechanical behaviour of grip-activated hand muscles

Publication

Understanding the mechanical behaviour of hand muscles might result in better grasping the onset of pathologies associated with the use of hand-held machines. With the aim of identifying the parameters of constitutive laws of such muscles, we developed an experimental apparatus, combining ultrasound elastography and mechanical indentation. Local shear modulus, static and dynamic stiffness were measured for five grip forces on 27 volunteers. Shear modulus and static stiffness were highly correlated and both increased when grip forces rose. Dynamics stiffness remained constant up to around 150 Hz (depending on the grip force) and then steeply increased when frequency went up. Larger the grip force, higher the dynamics stiffness with a stronger effect in the plateau region. These findings will be processed to build complex constitutive laws for grip-activated hand muscles.